We have the cloned fibroin DNA plasmids which cover 12 kb region upstream from the 5' end, 14 kb of entire mRNA coding sequence, l kb of an intervening sequence in the gene, and about 1 kb region downstream from the 3' end. DNA sequencing of these regions is being pursued. DNA sequencing of a proposed promoter region is already accomplished. We hope to reconstruct faithful transcription in vitro by mixing the purified gene with histones, non-histone proteins and RNA polymerase II. Through the reconstruction experiment we wish to understand regulatory mechanisms of silk fibroin gene.